Alcohol Blending Software - User’s Guide.
In order to properly use the blending functions contained in the Alcohol Blending Software package the user must be familiar with the relevant portions of the gauging manual regulations and examples thereof.
The software functions when properly used and programmed with accurate inputs that are within the bounds of the table values. From these inputs the program modules, represented by each spreadsheet, will replicate any permutation of the functions described in the tables as well as many additional functions relating to tracking, blending and accounting for alcohol use in a distilled spirits plant. Please consider all of these functions as tools and not a substitutes for close compliance with the regulations. If the tools are improperly applied or the user does not understand why certain inputs are required at certain times, serious errors in blending and accounting for alcohol can result. Some of these potential errors are demonstrated in ancillary worksheets in the program to give an idea of what their effect can be.
The first task is to take an accurate measurement of the temperature and density of the alcohol to be gauged. Using temperature and hydrometer readings we can determine the apparent proof at the sample’s current temperature and specific gravity reading. From these readings we can calculate the true proof at 60° Fahrenheit. The standard unit we will be using to measure our alcohol in is the Proof Gallon. A proof gallon has two characteristics; the first relates to its alcohol content and the second defines its volume with respect to temperature. The alcohol density of a proof gallon is defined as 50% alcohol or 100 proof. The volume is defined as 231 cubic inches of that alcohol at a temperature of 60°F. There is a third term, Wine Gallon, which defines a pure water volume of the same 231 cubic inches at the same temperature. It is one US Gallon and of water it weighs 8.328230 pounds by definition and has an assigned specific gravity of 1.0. The same 1 Gallon volume of 100 proof alcohol has a specific gravity of 7.78007 therefore one proof gallon of alcohol weighs 7.78007 pounds. This difference in weight is a measure of the relative density of these two substances.
Managing this difference in density and including temperature as an additional variable is what blending operations are all about.
The entire alcohol gauging regimen prescribed by the regulations is predicated upon all components being compared to the volume and density they would have if they were at the temperature of 60° Fahrenheit. This is known in the regulations as the True Proof at 60° F.
This construct is an idealized world, where everything is 60° F and it is the major assumption of the blending tables. All blending actions occur in this world and in order to enter it you have to normalize or adjust the apparent proof and actual temperature of the alcohol into this construct. To do so is to determine the True Proof at 60° F of the alcohol. This idealized world also applies to the water component of blending a batch of alcohol to a target proof so adding water at temperatures other than 60° can lead to blending irregularities. We will have more to say about this later.
This whole system only works only if you obtain an accurate measurement of the present temperature and apparent proof of the actual alcohol you are going to use. If your measurements of temperature and proof are not precise, with respect to the spirits being gauged, then the conversion into the true proof world of the tables will be inaccurate and your blend will not come out at the proof you intend.
Stated another way, one can measure the temperature and density of your sample for days on end and know the true proof of it as much as you want but if the sample is not the same temperature as the spirits you will actually use in your blending operations then the true proof you determine from that sample will not be the true proof of the spirits you will actually use in your batch. Consequently your blending calculations will be incorrect.
The hydrometers used are designed to read accurately on their face the proof of liquid alcoholic solutions at 60 degrees Fahrenheit; they read, 0 for water to 200 for absolute alcohol. There are 11 hydrometers needed to cover this entire range
Because of the temperature-density relationships of alcohol-water blends and the selection of 60 degrees for reporting proof, the hydrometer readings will be less than the true percent of proof at temperatures below 60 degrees Fahrenheit and greater than the true percent of proof at temperatures above 60 degrees Fahrenheit.
When alcohol is colder than 60° it is denser than it would be if it were 60°. Therefore the hydrometer will not sink as far into the alcohol. The proof reading is lower on the stem of the hydrometer indicating the proof is lower than it would be if the alcohol were 60°.
If the temperature of the alcohol is raised the volume of the alcohol will increase. It will become less dense and take up more volume. The hydrometer stem will sink farther into the alcohol and read a higher proof. At 60° the hydrometer will indicate the true proof of the alcohol and above that temperature will indicate a proof higher than the true proof.
The selection of 60° Fahrenheit as the standard is not simply arbitrary. It is a common enough ambient temperature so as to require the least amount of correction above and below that point. Within 20°of the standard is 40° and 80° and this temperature range covers most of the temperatures that distillers will find in their plants.
You might ask why not just measure all spirits in a 60° box where the sample and instruments are all the same temperature? This will always result in obtaining the true proof of the alcohol at 60° F. While this is true and will result in true proof being obtained it is not practical. The regulations suggest this much when they advise that “(if time permits, it is desirable to bring both the spirits and the instruments to room temperature)” This applies to the entire batch of spirits being measured not just the sample being tested. It is just not practical to do it this way.
For blending operations it is important to obtain a temperature of the alcohol as close as possible to that of the alcohol being used. If you are adding alcohol to a batch by volume that volume will be affected by the temperature of the spirits being used. If you are adding alcohol by weight colder alcohol will contain more proof gallons per pound than warmer spirits and therefore in order to know the correct amount of weight to add you must accurately know the temperature of the spirits being used in the batch.
When proofing alcohol always start by trying use a higher proof hydrometer than you think the alcohol might be. That way the hydrometer will not sink to the bottom of the beaker.
In your set of hydrometers you will see that the lower proof hydrometers are larger and you might think that because they are larger and displace more area that they will float more in high proof alcohol. That is not the case. They are also heavier than the high proof hydrometers . They are heavier in relation to the volume they displace in order to float in denser low proof mixtures. Low proof alcohol is denser because water is denser than alcohol. The low proof hydrometers are designed to float in relatively dense low proof alcohol. If you put them in less dense high proof alcohol they will go straight to the bottom.
The higher proof hydrometers are smaller and lighter relative to the volume they displace and they will not sink as far into a lower proof mixture. That way if it is not the right hydrometer to use on a given sample you will not have to fish it out of the bottom of the beaker.
Thermometers: There are many types of thermometers now available that are accurate to the 0.10 degree F. required by the regulations. If you use a glass hydrometer make sure that you get one that is accurate even though the thermometer itself is not completely 100% immersed in the alcohol. Of course the more the thermometer is immersed above the temperature reading of the thermometer the more accurate your reading will be. Most thermometers are not designed to read accurately when the temperature indication rises above the level of the liquid being measured. You must read the temperature under water so to speak. You can not remove the thermometer from the fluid and attempt to read the temperature or even raise the thermometer above the level of the alcohol to take a reading because evaporative cooling will quickly lower the temperature and you can watch the mercury drop as it does so.
Procedures for taking accurate readings of alcohol proof and temperature.
1. Mix the Alcohol. Most tanks and drums will develop a temperature gradient. Even if they are sitting on the ground the top may well be warmer than the bottom. Alcohol being less dense than water will tend to concentrate in the top of a tank or batch. For both these reasons it is a good idea to mix or stir the alcohol before taking a your proofing sample. You don’t want to agitate it so much that you introduce air bubbles into the alcohol. Air in alcohol will lower specific gravity and indicate a higher proof until it dissipates .
2. The hydrometers, thermometers and testing beakers should be kept clean and free of any oily substance.
3. All equipment should be as close as possible to the same temperature as the alcohol to be measured. This is much easier to do than to bring the temperature of the alcohol to that of the equipment.
Don’t bring instruments from the heated side of the shop into the unheated alcohol storage area and expect to get accurate temperature readings of the alcohol. Bring them in a half hour earlier and set them on the drums.
After awhile you will get to know the temperature of your shop in different seasons. There is a pretty steady base ground temperature that rises in the summer and falls in the winter. You can pretty much measure this temperature by measuring the temperature of the water coming into your shop. My shop runs from 72° in the summer down to 48° in the winter. Things sitting on or near the floor have about this water temperature. Try to match your instrument temperature to the ambient temperature of your shop.
4. Take your sample of spirits. Use a small portion of the sample to rinse out the beaker and douse the hydrometer. This helps bring the instruments to the same temperature as the spirits.
Holding the beaker with your hand will conduct heat out of your hand and into the sample. Assuming you are warmer than the sample. If you hand is colder than the sample, your hand will draw heat from it. When taking the temperature of the sample keep your hands off the beaker as much as possible. Also, the table the beaker is sitting on will add or remove heat from the sample depending on the temperature of the table.
5. Pour your sample into the beaker without introducing too much air into the sample. You may have to hold the beaker briefly to do this.
You want to avoid spilling any alcohol on the outside of the beaker. Any alcohol evaporating on the outside of the beaker will carry away heat and reduce the temperature of your sample below that of the alcohol being measured. Dry the outside of the beaker if any alcohol or water is on it.
6. Insert the thermometer as soon as the alcohol is placed in the beaker. While any air bubbles are rising to the surface and dissipating into the atmosphere. You need to get a fix on temperature as soon as possible so that it is as close to that of the alcohol being measured as possible.
Because of the large surface area of the beaker with respect to the sample size it will tend to absorb heat or lose heat with respect to the ambient temperature.
There is a temperature differential between the base ground temperature of the shop as measured by the water temperature and the ambient temperature of the shop. The ambient temperature fluctuates daily as much as 30° depending on the weather that day and the time of day it is.
For this reason it is advisable to measure the temperature and density of the sample at a temperature as close as possible to that of the alcohol being measured. In the summer, if you can arrange to do this in the morning when the ambient temperature is closest to the ground temperature so much the better. Don’t bring the alcohol sample from the unheated storage area into the heated shop and expect to get accurate temperature readings of the spirits actually being sampled. You will shorten the “life” of your sample as a representative sample if you do this. Remember, with these measurement you are not measuring the sample as an end in itself; you are measuring the spirits being sampled.
The large surface area of the beaker makes it also susceptible to cooling by drafts of air. Combined with any alcohol spilled on the outside of the beaker this will accelerate any evaporative cooling of the sample. So, keep the outside of the beaker dry and away from the fan, air conditioner or heater vent.
7. Put the hydrometer into the sample and bob it up and down to get the hydrometer closer to the sample temperature. Dry the stem so it does not cool by evaporation or “Weigh Down” the hydrometer.
Read the temperature of the alcohol from the thermometer. Try not to let the hydrometer rest against the side of the beaker.
8. To determine where the hydrometer stem is intersecting the alcohol look from below the surface of the alcohol at the point where the surface of the alcohol intersects the hydrometer stem. You should see an ellipse where the glass rises through the surface.
Now raise your eyes and the shape of that ellipse will begin to change. It will get smaller and eventually become a straight line. If you raise your eyes too far it will begin to become an ellipse again and become bigger. The point of smallest diffraction is the correct hydrometer reading.
Proof. The ethyl alcohol content of a liquid at 60 degrees Fahrenheit, stated as twice the percent of ethyl alcohol by volume. Proof gallon. A United States gallon of proof spirits, or the alcoholic equivalent thereof. Proof spirits. That liquid which contains one-half its volume of ethyl alcohol of a specific gravity of seven thousand nine hundred and thirty-nine ten-thousandths (0.7939) in vacuum at 60 degrees Fahrenheit referred to water at 60 degrees Fahrenheit as unity. Gallon or wine gallon. The liquid measure equivalent to the volume of 231 cubic inches. Meaning of terms. Old style § 186.11 New style § 30.11
The alcohol gauging procedures to determine true proof at 60° are covered in the regulations under §186.23 old style and §30.23 new style
Table 1 only applies when BOTH the proof and the temperature are whole numbers. In practice this never happens. The effect is to make Table 1 almost useless except in that special case.
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